This telegraph monitor was found in an American documentation for radio amateurs from the 1970s. The indicator is a common 1 mA full-scale milliammeter.
This simple field strength meter was found in a 1967 documentation. The transistor is germanium, and the...
This is yet another version of the light-controlled oscillator that can be found on this website. This...
Found in a 1969 documentation, this circuit for the 20 MHz band does not use a transformer. The circuit is...